The depletion of natural gas resources coupled with the improved technologies for biofuel production present a favorable scenario for entry into the biobutanol market. This process aims to produce butanol at a competitive price to oil and natural gas produced from petrochemical processes. As such, the proposed design takes an existing 40MM gpy corn ethanol plant and retrofits the plant to produce butanol via continuous fermentation of corn using a genetically engineered strain of Clostridia. The proposed design consumes 14.5 million bushels of corn per year and produces acetone, butanol and ethanol at a mass ratio of 12:58:1, respectively. The corn is undergoes traditional wet mill processing upstream, and is then fed as a slurry to the fermenters. The liquid fermentation products pass through liquid-liquid extraction followed by distillation to recover the butanol and acetone. The solids pass through a DDGS separation section and the vapor phase leaving the fermenters is combusted. This process intends to produce butanol, acetone, and DDGS for sale in the market. The plant has the capacity to operate 330 days per year and to produce 21.7MM gpy of butanol at 99.5% purity, 2.8MM gpy of acetone at 93.2% purity and 182,509 metric tons of DDGS per year. The plant is located in the Midwest United States in the Corn Belt. It has a return on investment of 12.07%.